A-to-I mRNA editing in fungi: occurrence, function, and evolution
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A-to-I RNA editing is an important post-transcriptional modification that converts adenosine (A) to inosine (I) in RNA molecules via hydrolytic deamination. Although editing of mRNAs catalyzed by adenosine deaminases acting on RNA (ADARs) is an evolutionarily conserved mechanism in metazoans, organisms outside the animal kingdom lacking ADAR orthologs were thought to lack A-to-I mRNA editing. However, recent discoveries of genome-wide A-to-I mRNA editing during the sexual stage of the wheat scab fungus Fusarium graminearum, model filamentous fungus Neurospora crassa, Sordaria macrospora, and an early diverging filamentous ascomycete Pyronema confluens indicated that A-to-I mRNA editing is likely an evolutionarily conserved feature in filamentous ascomycetes. More importantly, A-to-I mRNA editing has been demonstrated to play crucial roles in different sexual developmental processes and display distinct tissue- or development-specific regulation. Contrary to that in animals, the majority of fungal RNA editing events are non-synonymous editing, which were shown to be generally advantageous and favored by positive selection. Many non-synonymous editing sites are conserved among different fungi and have potential functional and evolutionary importance. Here, we review the recent findings about the occurrence, regulation, function, and evolution of A-to-I mRNA editing in fungi.
KeywordsRNA modification Deamination Adenosine Inosine Sexual reproduction Fusarium graminearum Neurospora crassa Epigenetic Adaptation ADAR ADAT Non-synonymous editing
We thank Ruonan Hei for assistance in preparing the illustrations and Drs. Cong Jiang, Qinhu Wang, and Chenfang Wang for fruitful discussions. We also thank Dr. Larry Dunkle at Purdue University for language editing the manuscript. This work was supported by grants from the National Science Fund for Excellent Young Scholars (Grant 31622045) and the National Youth Talent Support Program (Z111021802) to HL, and grants from the US Wheat Barley Scab Initiative and National Science Foundation to JX.
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Conflict of interest
The authors declare no competing financial interests.
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